Cladding Layer Research Articles

Fatigue life of S960 high strength steel with laser cladded functional surface layers

This study evaluates the fatigue life of S960 high-strength steel with laser-cladded layers of aluminium bronze, hard chrome, cobalt alloy, and stainless steel, using three-point bending tests. Our results demonstrate that while these cladded layers offer potential for enhanced surface properties, they generally reduce the material’s fatigue life due to alterations in the heat-affected zone and the introduction of microstructural defects at layer interfaces. The extent of fatigue life reduction varies with the type of cladded layer, highlighting the importance of optimizing laser cladding parameters to minimize detrimental effects and improve component longevity.

Enhanced surface wettability modification of Al2O3 for laser cladding ceramic-metal composite coatings

For the purpose of improving the wettability of ceramic reinforcement phases when heated in molten metal as well as improving particle reinforced metal matrix composite performance, electroless nickel plating was used to synthesize modified Al2O3@Ni powders for laser cladding. The results showed that a thin nickel shell uniformly covered the surface of the Al2O3 powders with a thickness of about 1.5 μm. It was shown that pretreatment significantly affects obtaining a complete and uniform nickel layer after nickel deposition. The composite coatings of Al2O3-316 L and Al2O3@Ni-316 L were prepared by laser cladding, respectively. The results showed that both of the microhardness of Al2O3@Ni-316 L cladding layers is higher (449.9HV0.05) than that of Al2O3-316 L (384.2HV0.05), the friction coefficient and wear rate of Al2O3-316 L are much lower than that of Al2O3@Ni-316 L cladding layer. The results indicated that Ni-coated Al2O3 powders could reduce the defects and obtain cladding coatings of high quality.

Influence of scanning speed on titanium alloy processed with TC4+Ni60/hBN composite powder by laser metal deposition coating technology

PurposeRegarding the broadening of the titanium alloy application field, the surface treatment coating of TC4 alloy has become an essential global research topic. This study aims to illustrate the titanium-based composite coating is created by laser cladding TC4+Ni60/hBN composite powder onto the surface of the TC4 alloy.Design/methodology/approachDifferent laser scanning speeds were initially selected to prepare TC4+Ni60/hBN titanium-based composite coating on the surface of TC4 alloy using RFL-C1000 Raycus fiber laser. Second, the cladding layers with different laser scanning speeds are composed of Ti2Ni, TiN0.3, TiC, TiB, α-Ti and other phases. Finally, precision balances, friction and wear testing machines were used to analyze and test the structure, phase, hardness, wear amount and friction coefficient of the composite coating and to study the effect of laser scanning speed on the microstructure and properties of the titanium-based composite coating.FindingsIt is evident that at the low laser scanning speed, the reinforcing phase agglomeration area is distributed in the substrate as a network. Increasing the laser scanning speed can reduce the cladding layer's friction coefficient and improve the cladding layer's hardness and wear resistance. But too high a laser scanning speed will cause defects such as pores and cracks in the cladding layer and also affect the cladding layer. The bonding performance of the layer and the substrate is optimal in this research at a laser scanning speed of 10 mm/s.Originality/valueThis research has practical value in improving the quality of surface treatment coating in modern aerospace and automotive companies.

Optimization model of overlap rate of laser cladding based on Gaussian function and top tangent model

As an important characterization of surface quality, the surface morphology of laser cladding coating directly affects the choice and difficulty of subsequent processing technology. The laser cladding coating is made of multi-track cladding layers, and the variation and optimization of overlap rate directly affect the quality of surface morphology. Firstly, the height, width and wetting angle of single-track cladding layer are substituted into the Gaussian function to obtain the characterization curve of single-track cladding layer, which can accurately characterize the profile curve of the single-track cladding layer. Then, by analyzing dual-track overlapping experiments with the varied overlap rates, it was found that the contour of the filled area is approximately a quadratic function curve. The area ratio of the filled area to the overlapping area first decreases and then increases with the increase of the overlap rate, reaching about 0.5 near the optimal overlap rate. Finally, a top-tangent overlapping model is developed based on the single-track characterization model of the Gaussian function and the forming characteristics of multi-track cladding layers. Experimental results show that the model can well characterize the multi-track cladding layers, and it is of great significance for optimizing the overlap rate of laser cladding and obtaining high-quality cladding layers.

Dual-mode microring resonator for humidity sensing with temperature compensation

On-chip refractive index (RI) sensors, which use resonant shifts of micro-cavities to detect environment change, have the advantages of high sensitivity, real-time detection, and compact footprints. However, the cross-sensitivity of the temperature variation severely interferes with sensing results. In this paper, we present a dual-mode microring resonator (MRR) with a cladding layer of polyhexamethylene biguanide hydrochloride (PHMB) for relative humidity (RH) sensing to overcome the limitation. Specifically, the influences of the RH-induced RI change of the PHMB cladding and temperature variations on the effective RIs of TE0 and TE1 modes can be decoupled based on the transmission spectral measurements. Using this method, we have demonstrated the temperature-compensated RH sensing which achieved a maximum sensitivity of −54.7 pm/%RH and a limit of detection of 0.8 %RH under the room temperature condition. Besides, a computational model based on the sensing response of the device was proposed and verified, which demonstrated that the structure can accurately measure changes in RH and temperature simultaneously. Our methodology has the potential to become a new reference for developing on-chip RI sensors with temperature compensation.

Microstructure and hardness of CoNiCrFeTix high-entropy alloy coatings prepared by laser cladding: Combining experimental and molecular dynamics simulation

Laser cladding technology offers several advantages over alternative coating methods, including rapid cooling, low dilution rate, and effective metallurgical bonding between the coating and matrix. However, there is limited understanding regarding the microstructures and properties of laser-cladded high-entropy alloy (HEA) coatings. Thus, our research aims to investigate the characteristics and performance of CoNiCrFeTix (x = 0.1, 0.3, 0.5, 0.7) HEA coatings, produced through laser cladding, on Q235 steel substrates We employ molecular dynamics (MD) simulation and experimental techniques to examine the impact of Ti element content on the structure and hardness of the cladding layer. The MD simulation accurately reproduces the melting and nucleation processes of crystal structures, providing insights beyond what is observable through experiments alone. Our results reveal that the cladding layer is predominantly composed of an FCC phase, with an increasing presence of a BCC phase as the Ti content rises. Correspondingly, experimental observations confirm that the CoNiCrFeTix HEA coating primarily consists of the FCC phase, while FeCr, Ni2Ti, and Co2Ti phases emerge with higher Ti content.The cladding layer exhibits a characteristic dendritic (DR) structure, where the interdendritic (ID) region expands as Ti content increases. Additionally, we conducted surface hardness testing on the cladding layer. The hardness of the cladding layer increases with the increase of Ti content, and the increase in Ti content enhances the stability of the dislocation density in the cladding layer.

Research on the effect of remelting on the epitaxial growth process of single crystal superalloy

In this paper, the remelting process is applied to Laser Directed Energy Deposition (L-DED) to repair single crystal superalloys. The main formation modes of stray grains in single crystal epitaxial growth were analyzed, and the inhibitory effect of remelting process on stray grains in single crystal epitaxial growth using L-DED was studied. Comparative experiments between remelting and non-remelting processes have been conducted. Three process parameters in the remelting process: power, z-axis lift and cladding-remelting interval time were studied. The impact of different remelting process parameters on single crystal epitaxial growth and the formation of stray grains has been studied. Remelting has been shown to effectively prevent the formation of stray grains during the solidification of the melt pool, which are otherwise caused by the presence of unmelted powder during the powder feeding phase of the L-DED process. A cladding layer without stray grains on both sides is obtained. After remelting, the epitaxial growth structure can achieve larger cellular and columnar dendritic zones and smaller primary dendrite arms. A favorable epitaxial growth structure was obtained in this paper, under the optimized remelting process window.

The investigation on the dynamic solidification behavior of the hybrid molten pool in layered bimetallic laser penetration welding

The dynamic solidification behavior of the hybrid molten pool in layered bimetallic DSS2205/X65 laser penetration welding has been investigated using high-speed photography and grayscale processing techniques. The results demonstrate that this welding process creates layered joints. Alongside the DSS2205 and X65 layers’ interconnection, an intermediate transition layer emerges proximate to their interface, exhibiting limited solute exchange. Understanding the dynamic solidification in the hybrid molten pool is crucial. Two Marangoni eddies form in the DSS2205 and X65 layers at the posterior end of the keyhole during welding. Despite encountering less external gas convection, the central transition zone of the hybrid pool undergoes rapid cooling, prompting preferential solidification. The grains then grow towards the sides due to the Marangoni eddies, resulting in a dumbbell morphology by wider ends and a narrower middle region. Thermodynamic calculations and microstructure observations reveal fine equiaxed grains in the transition zone influenced by the greater cooling rate and element distribution, while larger grains in the base layer, and columnar grains in the cladding layer. This confirms preferential solidification in the middle region. The study uncovers the intrinsic mechanism behind this phenomenon, offering valuable insights for controlling the microstructure, optimizing parameters, and enhancing mechanical properties in layered bimetallic composite joints using laser penetration welding.

Fatigue properties of titanium-clad bimetallic steel butt-welded joints

Titanium-clad (TC) bimetallic steel is a high-performance constructional material that yields promising application potential in future ocean and coastal civil engineering. However, the understanding on the mechanical behaviors of the corresponding weld joints is still limited. In this paper, a tensile-tensile fatigue experimental study was conducted on two types of butt-weld joints fabricated of hot-rolled TA2 +Q355B TC bimetallic steel. Based on the test results, the fatigue stress-life curves (S-N curve) of the two types of weld joints were obtained and subsequently compared with that of TC parent materials, other representative structural metals, that of butt-weld on other metals and the codified S-N curves provided by six structural/fatigue design standards. Most specimens of the two types of TC weld joints are initially cracked at the clad-to-cap weld. The bonding strength between clad and substrate layers exhibit a promising reliability under fatigue loadings. The fatigue resistance of the two types of TC weld joints is considerably less than the different TC parent materials studied. The fatigue lives of clad material (TA2) and substrate material (Q345/Q355B) are greater than that of TC weld joints. The S-N curves of two TC weld joints are considerably lower than that of high-strength steel series but higher than that of aluminum alloy 6061-T6. The design S-N curves of EC3 (Class 36) and IIW (Class 36) are too conservative for the two TC weld joints.

Higher entropy-induced strengthening in mechanical property of Cantor alloys/Zr-3 joints by laser in-situ eutectic high-entropy transformation

To effectively regulate the grain boundary infiltration in CoCrFeMnNi high-entropy alloy (Cantor alloys, HEA) caused by the violent atomic interdiffusion, the higher configuration entropy on Cantor alloys surface was designed and realized via eutectic high-entropy (EHEA) transformation. Meanwhile, to effectively alleviate the residual stress caused by the notable difference in the thermal expansion coefficient (CTE) between Cantor alloys and Zr-3 alloys, a cladding layer was applied to the HEA surface using laser cladding technology of Nb, followed by brazing to Zr-3 alloys with Zr63.2Cu filler. The cladding layer's microstructure comprised Nbss and FCC+(Co,Ni)2Nb eutectic structure, resulting from an in-situ reaction between Cantor alloys and Nb. The Nbss and FCC demonstrated good plasticity, and the (Co,Ni)2Nb Laves phase provided increased strength, endowing both good plastic deformation ability and strength of the cladding layer. Notably, the existence of EHEA in the laser cladding layer made the Cantor alloy entropy from 1.61 R to 1.77 R, greatly enhancing its thermal stability and suppressing the grave grain boundary infiltration. Joints produced via laser cladding with Nb-assisted brazing exhibited a complex microstructure (HEA/Nbss + FCC + (Co,Ni)2Nb/(Zr,Nb)(Cr,Mn)2 + (Zr,Nb)ss/(Zr,Nb)2(Cu,Ni,Co,Fe) + (Zr,Nb)(Cr,Mn)2 + (Zr,Nb)ss/Zr-3 and a significantly improved shear strength of 242.8 MPa at 1010 °C for 10 min, 42.4 % higher than that of directly brazed joints. This improvement was attributed to reduced grain boundary infiltration, alleviated residual stress due to CTE disparity, and eliminated micro-cracks in the brazing seam. This study presents an effective solution for reducing residual stresses and achieving reliable bonding between Cantor alloys and Zr-3 alloys, with potential applications in brazing CoCrFeNi-based HEA and Zr-3 due to the beneficial eutectic reaction between CoCrFeNi and Nb.

Axial compression test on strengthening concrete cylinders by Fe-SMA/FRP-HDPE tube and rubber concrete cladding layer

This paper proposed a new method to strengthen and repair concrete columns, which combined active and passive confinement. The method involved the use of iron-based shape memory alloy (Fe-SMA) strips to quickly exert active confinement to these columns, followed by the use of fiber-reinforced polymer (FRP) and high-density polyethylene (HDPE) tubes as external passive confinement to improve the load-bearing capacity, durability, and ductility of concrete columns. Rubber concrete that performs high energy consumption and certain strength was used as the cladding layer to improve the impact resistance of the concrete column. This paper explored the effect of this method on the bearing capacity performance of concrete columns through axial compression tests and set three test variables, including different net-spacing of Fe-SMA, different FRP wrapping forms, and different FRP layers. The test outcomes showed that all three test variables obviously improved the load-bearing capacity and ductility of concrete columns, peculiarly when applying active confinement. Eventually, this paper proposed a theoretical model to predict the peak compressive strength of the specimen, which can provide a reference for designing this active-passive confinement strengthening method.

Optimization and high-temperature wear characterization of Stellite alloy claddings developed using TIG welding on 56NiCrMoV7 die steel

In this study, Stellite 6 and Stellite 12 claddings were deposited on 56NiCrMoV7 hot-worked die steel using the Tungsten Inert Gas (TIG) welding process. Initially, single tracks were deposited using a full factorial design varying two process parameters - current (65, 75, and 85 A) and scan speed (400, 600, and 800 mm/min). The single tracks were then optimized based on dilution rate and microhardness. The optimized parameters were used to develop Stellite 6 and 12 multi-pass clad layers on 56NiCrMoV7. The evaluation of the microstructure of the claddings was done using an optical microscope, XRD, FESEM, EDX, and EBSD. The microstructure of the claddings consists of α-Co matric with M7C3, M23C6, and W2C carbides precipitated along the grain boundaries. Further microhardness and tribological performance were analyzed using Vicker's hardness tester and ball-on-disc tribometer, respectively. Stellite 12 claddings exhibited superior wear resistance and indicated reduced wear volume by 51.3 % at room temperature, 69.2 % at 450 °C, and 32 % at 550 °C compared to the base material and 53.2 % at room temperature, 37.3 % at 450 °C, and 24.1 % at 550 °C compared to Stellite 6 claddings. The KAM mapping showed higher dislocation density for Stellite 12 cladding. The combination of finer grains, higher hardness, and higher dislocation density resulted in higher wear resistance.

Corrosion Behavior of CMT Cladding Layer of AZ91 Magnesium Alloy Subjected to Friction Stir Processing.

Friction stir processing (FSP) was performed on an AZ91 magnesium alloy cladding layer fabricated by a cold metal transfer (CMT) technique. Electrochemical properties and immersion corrosion behavior of the cladding layer before and after FSP in 3.5 wt.% NaCl solution were investigated. After applying the FSP, the corrosion potential and corrosion current density of the cladding layer increased from -1.455 V to -1.397 V and decreased from 4.135 μA/cm2 to 1.275 μA/cm2, respectively. The results of OM and SEM displayed the refinement of grains and the dispersion of β-Mg17Al12 second phase in the friction stir processed (FSPed) cladding layer and more severe corrosion of the unprocessed sample. The corrosion rate of the FSPed cladding layer was lower, and a more compact corrosion product film was formed on the surface of the FSPed cladding layer. EDS results and XRD patterns showed that the corrosion products was mainly composed of Mg(OH)2. The increase in Al content in the α-Mg matrix, grain refinement, and fragmentation and dispersion of the β-Mg17Al12 second phase induced by FSP were the main factors that led to the improvement in corrosion resistance of the cladding layer of the AZ91 magnesium alloy fabricated by CMT.

Microstructure and properties of multi-layer laser cladding Cu-10Pb-10Sn anti-friction coating

The preliminary experimental results show that the laser cladding technology can produce a well-formed single-layer lead bronze cladding layer with a thickness of 250 μm. The ideal process parameters of the single-layer laser cladding test were selected to study the multi-layer cladding, and the microstructure and properties of the multi-layer cladding were evaluated. The results show that, the multi-layer cladding is composed of α-Cu, Cu41Sn11, Cu5.6 Sn, Pb, and SnO2 phases. There are fine equiaxed crystals at the top of the cladding layer while columnar crystals growing perpendicular to the fusion line at the bottom. The maximum hardness of cladding layer is 248.2 HV near the bottom fusion line. The wear mechanism of multi-layer cladding layer combines abrasive wear and adhesive wear, with wear weight loss and average friction coefficient of 0.0025 g and 0.1161, respectively. The average shear strength between the substrate and the cladding layer is 129 MPa, the shear fracture mode is ductile fracture. Compared with single-layer cladding, the anti-friction performance of multi-layer cladding is significantly improved.

In-situ synthesis of BN/Al18B4O33 heterogeneous core-shell nanowires with different BN shell thicknesses and the microstructure evolution mechanism

A simple method was developed for the controllable synthesis of novel BN-coated aluminum borate (Al18B4O33) heterogeneous core-shell nanowires using Al4B2O9 nanowhiskers as rigid templates. This method allows the fabrication of Al18B4O33 nanowires with BN coatings of different thicknesses. The phases, microstructures, and chemical compositions of the samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and other characterization techniques. The heterogeneous core-shell nanowires of BN/Al18B4O33 had diameters and tube lengths of 35–60 nm and 400–600 nm, respectively, and the thickness of the BN cladding shell was between 2 and 7 nm. The concentration of B* volatilized on the whisker surface could be controlled by varying the ammonia flow rate, which in turn regulated the thickness of the BN cladding layer. The thickness of the BN cladding changed more significantly when the ammonia flow rate was varied at the Al4B2O9 nanowhisker's decomposition temperature. The experimental results show that the BN on the BN/Al18B4O33 heterogeneous core-shell structured nanowires conforms to the vapor–solid (VS) growth mechanism.

Investigation on laser cladding Fe-based gradient coatings with hierarchical enhanced wear resistance on U75V railway steel

This study focused on the multilayer laser cladding of 15–5 precipitation hardening (PH) steel coating on U75V railway steel for improved surface performance. The effect of pearlitic substrate dilution action with high carbon content on microstructures and wear performance of PH steel coating with four deposited layers was investigated. Results showed that each cladding layer consisted of a similar multiphase mixture of martensite, retained austenite, and NbC carbides in the case of stepwise changes in chemical compositions induced by dilution effects. The wear resistance of the multilayered PH steel coating is closely related to the deposited layer number, reflected in a gradient increase in the wear rate with the increasing cladding layers. A comparative analysis against the U75V substrate showed substantial wear rate reductions of approximately 95 % and 4.5 % in the first and fourth layers, respectively. Besides, the cross-sectional microstructures were analyzed in detail to reveal the underlying friction-induced microstructural evolution of the gradient coating. The refinement of martensite laths controlled by dislocation reaction and the friction-induced austenite to martensite transformation was responsible for the superior wear resistance. The current experimental results could provide a new strategy for designing hierarchical enhanced wearable gradient coating for surface modification in railway components.

Novel photocatalysis-assisted mechanical polishing of laser cladding cobalt-based alloy using TiO2 nanoparticles

This paper presents a novel photocatalysis-assisted mechanical polishing method for cobalt-based alloy cladding layers using TiO2 nanoparticles. By leveraging the active oxygen species generated by the photocatalyst under illuminated conditions, surface oxidation reactions on cobalt-based alloys are initiated, thereby enhancing material removal efficiency. The underlying principles of photocatalytic oxidation are elucidated, particularly the promotion of oxidation by •OH when it interacts with the metal surface, leading to the formation of a CoO oxide film on the cladding layer surface and a subsequent reduction in surface hardness. An experimental platform was established, and research findings identified an etching time of 60 min and a TiO2 concentration of 10 wt% as optimal process parameters. Comparative analysis with pure mechanical polishing and chemical mechanical polishing revealed that photocatalysis-assisted mechanical polishing yielded superior surface roughness of 60 nm and a material removal rate of 63.8 μm/min.

INVESTIGATION OF THE BENDING BEHAVIOR OF INC625/SUS316L LASER-CLADDING LAYERS APPLIED TO GGG40

Laser cladding is a multi-purpose thermal coating technology whose application area has increased rapidly in recent years. It can be used for the purposes of obtaining a thick (mm to cm) layer on surfaces by the interaction of different materials in powder form (especially metallic and metal-matrix composite) with the laser beam, thus repairing, restoring, improving and protecting the surface resistance of various industrial metallic parts. It is normally used to refurbishment, create and repair metallic components, hydraulic mills, gears, shafts, turbine blades, drilling tools, and other static or dynamically loaded mechanical parts. The benefits of laser cladding over alternative technologies include better metallurgy (bonding, hardness or lower porosity) as well as reduced part deformation and stress due to lower overall heat input. The melting of substrate material ensures a good metallurgical bond between the cladding layer and the substrate material. However, the melting of the substrate material causes dilution. Therefore, the melting of the substrate material should be controlled and kept to a minimum because high substrate melting causes an increase in the dilution, which may degrade the mechanical and corrosion properties of the clad layer. The laser beam over the substrate materials creates temperature gradients in the thickness direction that can lead to mechanical deformation (such as bending) and changes in the microstructural and interface properties. Depending on the substrate type and production history, as well as the laser-clad powder properties and process parameters (power, feed rate, clad speed etc.) used in the application, the deformation properties of the cladded part and its bending behavior can change. In this study, INC625 and SUS 316L+INC625 clad layers were applied on a GGG40 substrate with optimized parameters and then subjected to bending tests. Bending-test results were examined comparatively and their microstructural properties were examined. Cladding powder feedstock material properties, substrate type and its thermo-physical properties, clad process parameters and surface preparation conditions, number and thickness of layers are the most important factors affecting the bending behaviour in laser-cladding applications and require optimization studies. The INC625 clad layer on the SUS316L bond layer has reduced the diffusional effects, and the hardness distribution has a more homogeneous profile. In this way, an increase in bending angles was observed. The highest bending angle of 32° was measured with dublex-clad layered samples.

Effect of solution and artificial aging heat treatment on the hardness, friction and wear properties of laser cladding and roll-formed 18Ni300 materials

Abstract 18Ni300 is widely used in precision moulds, national defence, and other engineering fields due to its high strength and toughness, and because its properties can be greatly changed after heat treatment. In this research, the 18Ni300 cladding layer was fabricated on 18Ni300 substrate using the laser cladding method and a solid solution artificial aging treatment was carried out to analyse its macro morphology and metallographic organization. Comparison of hardness, friction, and wear of cladding layers manufactured by laser cladding and of materials produced by rolling was performed before and after heat treatment. The results show that the solution and artificial aging heat treatment has a significant effect on the microstructure of the cladding layer fabricated by laser cladding. There are obvious differences in the organization and morphology of different parts of the cladding layer before heat treatment; the metallographic organization and morphology of different parts of the cladding layer after heat treatment are the same. The trend of change of material hardness before and after heat treatment is the same in that the cladding layer is greater than the rolled material and the hardness of the material after heat treatment is much greater than the hardness of the material before heat treatment. The hardness and wear resistance of the material after solution and artificial aging heat treatment has been significantly improved, and the impact on the rolled production material of the melted cladding layer manufactured by laser cladding is even greater.

Influence of structure and properties for laser cladding fe based alloy on 45 steel surface

This article uses 45 steel as the substrate and iron based alloy powder as the cladding material for mining machinery equipment. Laser cladding experiments were conducted without scanning speed to prepare 45 steel surface cladding iron based alloy layer samples. The samples were subjected to microstructure analysis, hardness, and acid corrosion resistance testing. The results show that the microstructure of the laser cladding layer is a fine-grained equiaxed crystal structure, and the hardness of the cladding layer is higher than that of the substrate. The corrosion rate of the cladding layer is low in various acid corrosive environments. The laser cladding layer is significantly higher in all aspects than the substrate, achieving the goal of high-quality preparation of iron based alloy coatings on the surface of 45 steel substrates.